Catalytic hydrodehalogenation of polyhalogenated hydrocarbons

ABSTRACT

A novel catalytic process involving complete hydrodehalogenation of halogenated aliphatic hydrocarbons in the presence of a hydrogen donor and a modified zeolite catalyst has been developed. The process is operated in a continuous flow mode and reaction products consist exclusively of hydrogen halide and hydrocarbons. The relative ratio of paraffins to olefins to aromatics obtained in the product distribution is a strong function of the ratio of hydrogen to reactant and the space velocity and temperature employed. The catalyst employed is a nickel metal modified shape selective zeolite that takes advantage of the hydrogenolysis ability of nickel and the acidic-shape selective properties of the zeolite.

This is a continuation of co-pending application Ser. No. 07/778,735, filed on Oct. 18, 1991, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a catalytic process for complete removal of heteroatoms from heteroatom-containing aliphatic hydrocarbons using a nickel-containing zeolite catalyst and is particularly suited for hydrodehalogenation of polyhalogenated compounds. The process is characterized by high conversion efficiencies without rapid catalyst deactivation. Ratios of paraffinic and aromatic products may be altered by modification of reaction conditions.

2. Description of Related Art

Various heteroaliphatic compounds are widely used commercially and industrially as solvents or reactants in the production of plastics, herbicides and other products. Unfortunately, many of these compounds are toxic and have posed significant problems in disposing of waste and residual material.

Present methods of disposing of toxic materials, particularly low molecular weight chlorinated liquid compounds, are not satisfactory. Landfills are inadequately protected against runoff or leakage into underground water supplies. Incineration frequently does not provide complete breakdown and in fact may produce other toxic compounds which are discharged into the atmosphere. Moreover, complete combustion of some compounds often requires high temperatures to obtain desired efficiency, resulting in high expenditure of energy.

Among the most common waste products are haloorganic compounds, including chlorinated hydrocarbons. There have been efforts to Develop efficient processes for removing one or more chlorine atoms from these compounds, especially the volatile chlorinated organics. A proposed alternative to incineration is biological and chemical waste conversion. In one example, chemical destruction of tetra- and trichloroethylenes in solution was achieved by reductive dechlorination with sodium naphthalenide (oku and Kimura, 1990). Another example of chemical destruction is the high-temperature gas phase reductive dehydrochlorination of chloroform and 1,1,trichloroethane by direct reaction with molecular hydrogen (Chuang and Bozzelli, 1986).

The major difficulty encountered in chemical reductive dehydrochlorination of these solvents is that many industrially important polychlorinated compounds, such as carbon tetrachloride, trichloroethanes, trichloroethylene, etc., are difficult to completely dechlorinate using economically acceptable routes. In principle, a catalytic process offers possibilities for chemical conversions and a number of studies have focused on hydrodehalogenation. However, these studies have been limited to only partial removal of the halogen, as in dehydrochlorination of 1,1,2-trichloroethane to 1,1-dichloroethylene over alumina (Mochida et al., 1978) or to mixtures of 1,1- and 1,2-dichloroethylenes over an alkali ion/SiO₂ catalyst (Gokhberg et al., 1989). Also, zeolite catalysts have been employed to achieve partial dechlorination of a variety of di- and tri-chlorinated hydrocarbons (Diesen, 1983). Attempts at more extensive catalytic dechlorinations with zeolite Y and mordenite catalysts have resulted in rapid catalyst inactivation due to deposition of carbonaceous material on the catalyst surface (Imamura et al., 1989; Weiss et al., 1982). As illustrated in the present application, shape selective zeolite catalysts, similar in composition to those employed by Diesen (1983) and Butter, et al. (1975) also exhibit rapid catalyst deactivation when employed under reaction conditions in which complete dechlorination of polychlorinated reactants is attempted.

In general, efforts to remove multiple chlorine atoms from hydrocarbon compounds have not been successful, particularly where zeolite catalysts have been used. To date, every reported catalyst study in which complete dehalogenation of polyhalogenated reactants was attempted has failed as a result of rapid catalyst deactivation. Major drawbacks of attempts to use catalytic methods include inefficiency of the dechlorination process, relatively rapid poisoning or inactivation of the catalyst and/or economically unacceptable routes of conversion.

SUMMARY OF THE INVENTION

The present invention provides the first successful continual catalytic process for the complete hydrodehalogenation of polyhalogenated molecules. The method is especially efficient in dehydrohalogenation of polychlorinated aliphatic hydrocarbons. The process of the invention generally results in 100% conversion to hydrocarbons and hydrogen chloride, without rapid deactivation of the metal-containing zeolite catalyst used in the conversion reaction.

The process developed is also successful in the removal of heteroatoms from a wide range of heteroatom-containing organic compounds. Examples of heteroatom-containing feedstock compounds include oxygen, sulfur, nitrogen and halogen-containing aliphatic hydrocarbon compounds.

In the practice of the present invention, one generally utilizes a continuous flow process wherein a gaseous phase containing one or more heteroatom-containing aliphatic hydrocarbons is passed over a nickel metal-containing zeolite catalyst. The feedstream typically includes a hydrogen donor. The reaction is generally conducted at temperatures above 300° C.

In one aspect of the invention, feedstocks containing one or more halogenated hydrocarbons are completely converted to nonhalogen containing hydrocarbons in the gaseous phase using initial conversion temperatures between about 300° and 500° C., preferably 450° C., for a period of time sufficient to initiate conversion to nonhalogen containing products. Although the time of contact at the initiation temperature may vary depending on the halogenated hydrocarbon and the hydrogen donor used in the feedstock, the inventors have found that about one hour at the initiation temperature is satisfactory. Once initiated, the reaction temperature may be lowered to approximately 325° C. At this temperature 100% conversion will continue at the same efficiencies in product distributions as observed at constant temperatures of 350° C. and above.

The catalyst found useful for this reaction is a metalmodified zeolite catalyst. A ZSM-5 zeolite catalyst containing free nickel metal is particularly preferred. Efficient halogen stripping from polyhalogenated aliphatic hydrocarbons is not observed unless the catalyst contains elemental nickel metal. ZSM-5 zeolite catalyst alone, aluminum oxide or ZSM-5/Al₂ O₃ catalyst do not provide efficient conversions of polychlorinated materials such as, for example, 1,1,1-trichloroethane. Pure HZSM-5 catalyst, for example, is rapidly deactivated when hydrodechlorination of 1,1,1-TCA is attempted. This loss of activity may be attributed to coke formation on the catalyst as revealed by spectroscopic and scanning electron microscopy (SEM) analysis. SEM analysis of spent catalysts reveals tiny fibers of coke on the exterior surface sites.

In contrast to pure ZSM-5 or Al₂ O₃ catalysts, the nickel ZSM-5/Al₂ O₃ bifunctional catalysts used in the method of this invention when combined with addition of an appropriate hydrogen donor to a feedstock stream containing a polyhalogenated aliphatic hydrocarbon achieves dechlorination of these molecules without experiencing rapid catalysts inactivation. An effective catalyst is prepared by mixing ZSM-5/Al₂ O₃ with an aqueous solution of a nickel salt such as nickel nitrate. The Ni(NO₃)₂ /ZSM-5/Al₂ O₃ mixture obtained after drying is calcined to convert the nickel nitrate to nickel oxide which is subsequently reduced to elemental nickel such as by hydrogen reduction. As shown by scanning electron microscope analysis, micron sized groupings of nickel atoms are disbursed uniformly throughout the solid sample. Percent nickel loading may be controlled by variation of the concentration of the nickel salt used in the original aqueous solution. Typically, nickel loadings from 10%35% provide an efficient catalyst, although hydrodehalogenations have been observed with nickel loadings as low as 1%. At low percent loadings, however, catalyst efficiency rapidly deteriorates, usually within the first few hours of the conversion reaction.

While the invention has been illustrated with a ZSM-5 zeolite, it is anticipated that the catalyst is not necessarily limited to the ZSM-5 type zeolite. Other synthetic shape selected zeolites with other pore sizes and activity expected to be useful are available for example, ZSM-11 and ZSM-22 and the like. Moreover, although the catalyst used in demonstrating this invention has a silicon to aluminum ratio of 30 to 1, it is in fact possible to vary this silicon to aluminum ratio from approximately 10 to 120 while maintaining the ZSM-5 pore structure. It is well known that the relative strength of the catalytic acid sites increases with decreasing aluminum content in ZSM-5 materials. Therefore, it is expected that catalyst formulation with respect to catalyst activity and longevity may be improved by changing the silicon aluminum ratios in selected zeolite catalysts.

Feedstocks used in the conversion reaction typically comprise an aliphatic polyhalogenated hydrocarbon and a hydrogen donor. A hydrogen donor is used in order to obtain and maintain complete dechlorination of the polychlorinated reactants. Generally, it has been found that hydrogen, or hydrogen in combination with water or methanol, may serve as hydrogen donors. When hydrogen alone is used as a hydrogen donor, an excess of hydrogen over the organic reactant is generally employed. The excess hydrogen may be recycled in the reaction. Increased economy of the conversion may be obtained by combining hydrogen with other hydrogen donor additives such as water or methanol. Water and methanol are particularly attractive because they are less expensive than hydrogen and may be used with hydrogen for efficient conversion to products.

Continuous dechlorination has been found to occur with temperatures on the order of about 325° C. and higher. At lower temperatures catalyst lifetimes have decreased, apparently due to coke deposition. With respect to commercialization, the lower the reaction temperature the more attractive the process economics with respect to energy consumption, capital equipment costs, and maintenance needs. It will be appreciated that lower operating temperatures may be achieved via improvements in both catalyst composition and/or the nature and concentration of the hydrogen donor atoms added to the reaction feed. While variation is possible, the inventors have found that, in general, the reaction may typically be run efficiently between about 300° and 500° most preferably at a temperature between about 350° and 400° C. Alternatively, the reaction may be initiated at a temperature of 350° or above and subsequently lowered to a maintenance temperature of around 325° C. It has been found that if the reaction is not initiated at the higher temperature before dropping the temperature to about 325° C., reaction efficiency decreases.

While the invention has been demonstrated with a nickel metal loaded zeolite catalyst, it should be noted that many other transition metals besides nickel also exhibit hydrogenolysis activity; for example, metals such as cobalt, ruthenium, rhodium, platinum and palladium are used extensively for this purpose. Expense might be one factor to consider in developing other metal loaded zeolite catalyst for the practice of the present invention. Cobalt and iron may be attractive for consideration because they are relatively inexpensive. Moreover, it may well be that selective use of small amounts of rare metals in combination with larger amounts of elements such as nickel, cobalt and the like may be especially useful without adding unduly to the expense. Alternatively, mixed metal containing zeolite catalysts, as well as the presence of various metal ions either entrapped or as part of the framework are not intended to be excluded from the ambit of the invention.

An important aspect of the invention is the ability of the catalyst to convert polyhalogenated compounds completely to products free of the halogen atoms. Examples of compounds that may be totally converted to the corresponding hydrogen halide and hydrocarbon reaction products are trichloroethylenes and trichloroethanes. Typical examples of polychlorinated hydrocarbons include 1,1-dichloroethane, 1,1-dichloroethylene, 1,2-dichloromethane, 1,1,1- and 1,1,2-trichloromethane and the like. Perchlorinated hydrocarbons such as tetrachloroethylene are also readily hydrodechlorinated using the process of the invention.

Additionally, the inventors' hydrodehalogenation process readily hydrodebrominates polybrominated aliphatic hydrocarbons, including 1,2-dibromoethane and like compounds. The conversion process may also be practiced with a wide range of other materials containing hetero atoms such as oxygen, nitrogen or sulfur, represented by common solvent and liquid wastes such as ethyleneglycol, acetone, various alcohols and a variety of sulfur-containing compounds. One hundred percent conversion of these compounds to pure hydrocarbons has been demonstrated using the described process.

Mixed halogenated compounds are also hydrodehalogenated. A particular compound of interest is trichlorotrifluoroethane, shown to be completely dehalogenated using the disclosed process. Several modifications of the reaction conditions are envisioned, particularly in devising methods to alleviate potential adverse effects of hydrogen fluoride that may affect the integrity of the catalyst. Methods such as adsorption or reaction with added neutralizing substances in the feedstream would be a consideration.

It will be appreciated that it may be desirable to alter the ratio of distribution products obtained from the various reactants that might be employed. This is readily achieved by altering hydrogen to reactant ratio, temperature and/or space velocity. Such changes, improvements and modifications are well within the range of practice and knowledge to those of skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the product distribution in conversion of trichloroethylene over 10% Ni/H-ZSM-5/Al₂ O₃ in the presence of hydrogen and water at a constant temperature of 425° C.

FIG. 2 shows product distribution as a function of reaction temperature in the conversion of 1,1,2-TCA over 10% Ni/ZSM-5/Al₂ O₃ catalyst in the presence of hydrogen and water. Ratio of [H₂ ]/[1,1,2-TCA]=120:1, WHSV (TCA)=0.3 hr-1.

FIG. 3 shows conversion and product distribution for methylene chloride in the presence of methanol over Ni/H-ZSM5/Al₂ O₃, methylene chloride flow was 1.3 ml/min, methanol flow 1.3 ml/min, H₂ flow at 12 ml/min, WHSV (MeCl₂ +MEOH) at 1.7 ml/hr, at 450° C. for 175 min, the lowered to 350° C. Catalyst mass was 600 mg.

DETAILED DESCRIPTION OF THE INVENTION Reactor

A fixed-bed continuous flow microreactor operating at atmospheric pressure was employed. Catalyst was placed in the center of a 1/4 inch×6 inch stainless steel reactor tube mounted vertically in a bored cylindrical block aluminum furnace. The furnace temperature was adjusted and maintained using an Omega Engineering CN-2010 Series programmable temperature controller. Gas flows (H₂ and He) were measured using calibrated flow meters. The liquid reactant was provided to the reactor by bubbling hydrogen through a thermostated container of the liquid. All transfer lines were heated to eliminate condensation of the liquid. The amount of liquid reactant provided as vapor was determined by periodic weighing of the liquid containing vessel. Conversion studies were carried out over a temperature range of 250° to 450° C. using 400 mg samples of catalyst.

Catalyst

The particular form of ZSM-5 used in the present work had a silicon to aluminum ratio of 30. The sodium cations present in the zeolite were exchanged for NH₄ ⁺ by contacting the catalyst with a solution of (NH₄)₂ SO₄. Specifically, this cation exchange was carried out using weight ratios of 1 g (NH₄)₂ SO₄ : 1 g ZSM-5: 10 g H₂ O. The NH₄ -ZSM-5 material so obtained was dried at 120° C. and then calcined at 550° C. for 3 hours. The resulting solid was mixed with 0.5 M HNO₃ at 70° C. for 4 hours at a mixing ratio of 1 g of catalyst per 40 mL of HNO₃ solution. The solid catalyst in the form of H-ZSM-5 was filtered from solution and dried at 120° C. The resulting solid was blended with Al(OH)₃ at a weight ratio of 40 parts zeolite to 60 parts Al(OH)₃. This blend was then added to a solution of nickel(II) nitrate and the resulting solution evaporated to dryness. The nickel loading of the final catalyst was determined by the volume and concentration of the Ni(NO₃)₂ solution employed. The resulting solid obtained was then calcined at 550° C. for 2 hours to convert the Ni(NO₃)₂ to nickel oxide and the Al(OH)₃ to Al₂ O₃. The resultant solid NiO/ZSM-5/Al₂ O₃ was cracked and sieved to 18-50 mesh (i.e., 1000 to 300 micron sized particles). The nickel oxide was reduced to elemental nickel immediately prior to use by hydrogen reduction. Alternately the high temperature calcination of Ni(NO₃)₂ to NiO was replaced by direct temperature programmed H₂ reduction of the Ni(NO₃)₂ as described by Bartholomew and Farrauto (1976). The % Ni loading of the catalyst was defined as the weight ratio of Ni to the combined weight of ZSM-5+Al₂ O₃ times 100.

Reaction Product Analysis

Reaction products were determined by on-line gas chromatography (GC) using a 30 meter megabore (0.53 Mm) GS-Q column operated in a temperature programmed mode over a temperature range of 70°-236° C. and helium carrier gas flow rate of 8 ml/min. FID detection was employed. Using this system, excellent separations were obtained for low molecular weight hydrocarbons up through C₁₁. In addition, possible partially dechlorinated intermediates (e.g., dichloroethylenes, vinyl chloride) were well resolved and easily identified in the presence of a complex hydrocarbon mixture. Hydrocarbon products and GC response factors were obtained by calibrations with known pure compounds. A Varian Model 4400 integrator was used to compute and record peak areas. Reaction product distributions were reported in terms of product selectivity expressed relative to carbon atom number.

Chlorine and Hydrogen Chloride Analysis

A number of experiments were carried out in which the catalyst exhaust gases were analyzed for chlorine and hydrogen chloride content. Molecular chlorine was determined by bubbling the exhaust gases through 0.1 M KI solution and then measuring any iodine formed by Cl₂ Oxidation via an iodometric titration for liberated I₂. Hydrogen chloride analysis of the catalyst exhaust was achieved by allowing these gases to bubble through a 0.01 M NaOH solution containing 1.5% hydrogen peroxide. Any Cl₂ present in the exhaust gas would be converted to chloride ion via the reaction:

    Cl.sub.2 +2 NaOH+H.sub.2 O.sub.2 →2 NaCl+2 H.sub.2 O+O.sub.2

The total chloride in the solution was determined spectrophotometrically by complex formation with mercury(II) thiocyanate. The HCl in the exhaust gas was calculated by first subtracting the chloride contribution from Cl₂ as determined iodometrically. Negligible chlorine content in the exhaust gas was found; therefore, the total extent of the spectrophotometric complex formation was attributed to the HCl content of the exhaust gases. Under none of the reaction conditions employed in this work was molecular chlorine found as a reaction product. Typically, large amounts of chlorine representing at least 97% of the total theoretically available chlorine under reaction conditions of complete dechlorination of starting material were found.

EXAMPLE 1

The following example illustrates that a polychlorinated hydrocarbon undergoes complete removal of chlorine under the reaction conditions described. In this example, trichloroethylene is used as an example of a multichlorinated substrate.

Hydrodechlorination of Trichloroethylene

A feedstream containing trichloroethylene and hydrogen was fed over a 10% Ni/H-ZSM-5/Al₂ O₃ catalyst at a reaction temperature of 425° C. The trichloroethylene GHSV was 1260 hr⁻¹. Hydrocarbon product distribution as a function of time onstream obtained in continuous conversion is shown in FIG. 1. No chlorinated hydrocarbons were identified in the product. Product paraffins were measured initially at about 70%, decreasing to about 50% after 9-10 hrs. The remaining products were aromatics and olefins. Yield of olefins was negligible. Conversion of trichloroethylene was 100%.

EXAMPLE 2

This example illustrates removal of chlorine from a trichlorinated aliphatic hydrocarbon.

Hydrodechlorination of 1,1,2-trichloroethane

A feedstock of 1,1,2-trichloroethane and hydrogen was fed over a nickel-loaded (10% by weight) ZSM-5 catalyst over a period of 11 hrs. Table I shows variations in product distribution with time onstream at 350° C. at a H₂ /TCA ratio of 6:1. Table II illustrates product distribution under the same conditions except that the H₂ /TCA ratio was reduced to 3:1. Table III illustrates the effect of increasing the temperature to 450° C. at a H₂ /TCA ratio of 3:1. In these tables, product selectivities are expressed in terms of carbon atom numbers (taking into account the number of carbon atoms per product molecule) and have been normalized to 100% with respect to carbon atom distribution among the pure hydrocarbon products.

Complete conversion of TCA at temperatures above 350° C. was achieved without the formation of chlorinated hydrocarbon byproducts. As shown in Table I, it was possible to maintain 100% dechlorination of 1,1,2-TCA for 11 hrs at 350° C. at a H₂ to TCA reactant ratio of 6:1 and a space velocity of 1260 hr⁻¹. Under these conditions, paraffin formation is strongly favored.

Continued catalytic conversion of the 1,1,2-TCA was achieved and maintained for an approximate 9-hr. period even when the H₂ /TCA reactant ratio was reduced to 3:1 (Table II). In these experiments, helium was substituted as make-up gas to compensate for the decreased flow of H₂ and thus provide a constant space velocity of 1260 hr.⁻¹. Two major trends were noticeable in comparing data from the experiments at H₂ /TCA reactant ratios of 6:1 (Table I) and 3:1 (Table II). The first difference was that although 100% conversion of the 1,1,2-TCA is maintained in both experiments over the 11-hr period involved, complete dechlorination was lost during the latter stages of the run at reduced H₂ flow. This is shown in Table II after 9 and 11 hrs. of time on-stream where measurable amounts of dichloro- and monochloroethylene were detected in the product stream for the first time. The second notable difference in contrasting data in Tables I and II was a substantial difference in hydrocarbon product distributions, especially with respect to decreased paraffin and increased aromatic formation at the lower H₂ /TCA reactant ratio.

                  TABLE I                                                          ______________________________________                                         Variations in Product Distributions with Time On-Stream (TOS)                  in the Conversion of 1,1,2-Trichloroethane (TCA)                               at 350° C. and a H.sub.2 /TCA Ratio of 6:1                              ______________________________________                                         TOS (Hr):   1.0     2.5     4.5    8.0   11.0                                  Conversion (%):                                                                            100.0   100.0   100.0  100.0 100.0                                 Product Distribution                                                           Chlorinated 0.0     0.0     0.0    0.0   0.0                                   Hydrocarbon                                                                    Hydrocarbon 100.0   100.0   100.0  100.0 100.0                                 Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2     0.4     0.3     0.2    0.2   0.3                                   C.sub.3     0.1     0.0     0.0    0.0   0.0                                   C.sub.4     0.0     0.0     0.0    0.0   0.0                                   Selectivity 0.5     0.3     0.2    0.2   0.3                                   Paraffins                                                                      C.sub.1     8.9     7.2     7.7    8.5   8.9                                   C.sub.2     18.4    16.4    13.6   14.2  15.3                                  C.sub.3     36.0    41.3    4.0    40.9  40.4                                  C.sub.4     6.5     5.2     4.4    4.6   4.6                                   C.sub.5+    0.1     0.0     0.1    0.0   0.1                                   Selectivity 69.9    70.1    66.8   68.2  69.2                                  Aromatics                                                                      Benzene     7.2     9.9     10.6   10.5  10.6                                  Toluene     10.5    13.7    15.1   14.1  13.8                                  C.sub.8     3.7     5.3     5.8    5.0   4.7                                   C.sub.9     1.0     0.5     0.6    0.8   0.3                                   C.sub.10 + C.sub.11                                                                        7.2     0.9     0.9    1.2   1.0                                   Selectivity 29.6    30.6    33.0   31.6  30.4                                  ______________________________________                                          NOTE: Reactor Conditions: Wt. of Catalyst = 400 mg; [H.sub.2 ]/[TCA] =         6/1; Space Velocity = 1260 hr.sup.1 ; % Nickel Loading of Catalyst = 10%       by weight.                                                               

                                      TABLE II                                     __________________________________________________________________________     Variations in Product Distributions with Time On-Stream in the Conversion      of                                                                             1,1,2-TCA at 350° C. Under a Reduced Hydrogen Flow [H.sub.2             /He/TCA = 3/3/1]                                                               __________________________________________________________________________     TOS (hr):    1.0 2.0 3.0 4.5 6.5 9.0 11.0                                      Conversion (%):                                                                             100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                     Product Distribution                                                           trans-1,2-Dichloroethylene                                                                  0.0 0.0 0.0 0.0 0.0 3.3 11.3                                      cis-1,2-Dichloroethylene                                                                    0.0 0.0 0.0 0.0 0.0 3.9 18.0                                      Vinyl chloride                                                                              0.0 0.0 0.0 0.0 0.0 0.1 0.7                                       Hydrocarbon  100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              92.7                                                                               70.0                                      Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2      0.7 0.8 1.1 1.3 1.9 3.2 7.6                                       C.sub.3      0.6 0.6 1.0 1.2 1.9 6.5 8.1                                       n + i-C.sub.4                                                                               0.0 0.0 0.0 0.0 1.1 2.4 4.1                                       2-C.sub.4    0.0 0.0 0.0 0.0 0.0 1.2 3.4                                       Selectivity  1.3 1.4 2.1 2.5 4.9 13.3                                                                               23.2                                      Paraffins                                                                      C.sub.1      6.6 5.4 6.2 5.9 7.1 7.6 8.1                                       C.sub.2      4.5 3.3 3.7 3.0 3.0 3.1 3.1                                       C.sub.3      18.6                                                                               17.7                                                                               18.0                                                                               17.7                                                                               13.9                                                                               11.0                                                                               7.7                                       i-C.sub.4    13.6                                                                               11.6                                                                               12.7                                                                               12.2                                                                               10.0                                                                               8.0 5.8                                       n-C.sub.4    5.4 5.1 5.5 5.9 5.0 3.4 2.3                                       C.sub.5+     3.6 3.8 4.8 5.0 5.5 4.8 4.3                                       Selectivity  52.3                                                                               46.9                                                                               50.9                                                                               49.7                                                                               44.5                                                                               37.9                                                                               31.3                                      Aromatics                                                                      Benzene      5.9 6.2 5.7 5.8 5.1 4.1 2.5                                       Toluene      19.9                                                                               21.7                                                                               21.0                                                                               19.4                                                                               20.4                                                                               18.3                                                                               13.8                                      C.sub.8      14.5                                                                               15.4                                                                               15.4                                                                               14.5                                                                               17.6                                                                               18.4                                                                               18.8                                      C.sub.9      1.7 2.8 3.0 3.4 4.1 4.8 7.2                                       C.sub.10 + C.sub.11                                                                         4.4 5.6 3.9 4.7 3.4 3.2 3.2                                       Selectivity  46.4                                                                               51.7                                                                               47.0                                                                               47.8                                                                               50.6                                                                               48.8                                                                               45.5                                      __________________________________________________________________________      NOTE: Catalyst and reactor conditions were identical to those in Table I       with the exception of a reduced H.sub.2 flow and addition of He makeup ga      to maintain space velocity.                                              

                                      TABLE III                                    __________________________________________________________________________     Variations in Product Distributions with Time On-Stream in the Conversion      of                                                                             1,1,2-TCA at 450° C. and a H.sub.2 /TCA Ratio of                        __________________________________________________________________________     3:1                                                                            TOS (Hr):    1.0 2.0 3.0 11.0                                                                               14.0                                                                               22.0                                                                               24.0                                      Conversion (%):                                                                             100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                     Product Distribution                                                           Chlorinated Hydrocarbon                                                                     0.0 0.0 0.0 0.0 0.0 0.0 0.0                                       Hydrocarbon  100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                     Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2      3.7 1.6 1.2 2.3 2.3 2.5 2.6                                       C.sub.3      2.0 0.3 0.3 0.5 0.8 0.9 0.9                                       n + i-C.sub.4                                                                               0.2 0.0 0.0 0.0 0.0 0.0 0.0                                       2-C.sub.4    0.3 0.0 0.0 0.0 0.0 0.0 0.0                                       Selectivity  6.2 1.9 1.5 2.8 3.1 3.4 3.5                                       Paraffins                                                                      C.sub.1      6.2 20.3                                                                               13.8                                                                               25.0                                                                               13.3                                                                               14.9                                                                               14.8                                      C.sub.2      2.1 15.5                                                                               11.0                                                                               19.8                                                                               7.2 8.3 8.5                                       C.sub.3      10.3                                                                               7.2 5.8 9.8 16.7                                                                               16.3                                                                               14.7                                      i-C.sub.4    1.4 0.1 0.1 0.1 0.6 0.5 0.4                                       n-C.sub.4    1.1 0.2 0.1 0.1 0.6 0.6 0.5                                       C.sub.5+     0.2 0.0 0.0 0.0 0.0 0.0 0.0                                       Selectivity  21.3                                                                               43.3                                                                               30.8                                                                               54.8                                                                               38.4                                                                               40.6                                                                               38.9                                      Aromatics                                                                      Benzene      16.5                                                                               20.0                                                                               16.0                                                                               19.2                                                                               18.9                                                                               19.0                                                                               19.9                                      Toluene      29.9                                                                               12.1                                                                               8.9 9.5 19.0                                                                               17.8                                                                               18.1                                      C.sub.8      14.2                                                                               9.5 6.9 1.7 5.6 4.9 4.8                                       C.sub.9      11.8                                                                               13.0                                                                               26.5                                                                               0.4 1.0 0.6 0.9                                       C.sub.10 + C.sub.11                                                                         0.1 0.2 9.4 11.6                                                                               14.0                                                                               13.7                                                                               13.9                                      Selectivity  72.5                                                                               54.8                                                                               67.7                                                                               42.4                                                                               58.5                                                                               56.0                                                                               57.6                                      __________________________________________________________________________      NOTE: Catalyst and reactor conditions were identical to those in TABLE I       with the exception of a reduced H.sub.2 flow and addition of He makeup ga      to maintain space velocity.                                              

Reactions carried out at 450° C. resulted in the conversions and product distributions shown in Table III. Complete conversion and dechlorination of the reactant trichloro-solvent was maintained over the 24-hr period of this experiment. There was a noticeable shift in hydrocarbon product distribution favoring formation of aromatics by comparison with reactions run at 350° C. As shown in Table III, there was a high aromatic yield, favoring monocyclic aromatics, during the initial hour of conversion. Overall, there were significant variations with hydrocarbon product distributions during the first few hours of conversion with a steady-state distribution being achieved at longer reaction times.

EXAMPLE 3

This example illustrates the importance of incorporating elemental nickel in the zeolite catalyst used for the dehydrohalogenation reaction.

1,1,2-Trichloroethane Conversion over H-ZSM-5 Catalyst

1,1,2-Trichloroethane was converted under the same conditions as Example 2 except that a ZSM-5 catalyst was used in place of the nickel-loaded ZSM-5 catalyst. As shown in Table IV, incomplete dechlorination of TCA was obtained even during the initial time onstream. For example, the percentage conversion of the TCA dropped from 100% to 34.4% after only 150 minutes of onstream conversion. Additionally, even during the initial reaction stage, the product distribution consisted overwhelmingly (98%) of chlorine-containing molecules (e.g. dichloroethylenes). Clearly, unmodified H-ZSM-5 is not an effective catalyst for obtaining complete dechlorination of this polyhalogenated reactant.

EXAMPLE 4

This example illustrates the conversion of a multihalogenated aliphatic hydrocarbon over a nickel-containing zeolite catalyst.

                                      TABLE IV                                     __________________________________________________________________________     Variations in Conversion Percentages and Product Distributions with            Time On-Stream in the Conversion of 1,1,2-Trichloroethane Over a               Pure H-ZSM-5 Catalyst (No Added Ni) at 350° C. and 450° C.                        Product Distribution                                                           trans-1,2-                                                                           cis-1,2-                                                                             1,1-                                              TOS Temp                                                                               % Conversion of                                                                         Dichloro-                                                                            Dichloro-                                                                            Dichloro-                                                                            Vinyl                                       (min)                                                                              °C.                                                                         1,1,2-TCA                                                                               ethylene                                                                             ethylene                                                                             ethylene                                                                             Chloride                                                                            Hydrocarbon                            __________________________________________________________________________      35 350 100.0    35.7  58.9  0.1   3.5  1.8                                     70 350 100.0    28.9  61.7  0.2   7.6  1.6                                    110 350 71.5     21.6  61.5  0.3   15.4 1.2                                    150 350 34.4     18.2  53.8  0.5   25.2 2.3                                    230 450 100.0    18.3  51.3  0.4   28.5 1.5                                    270 450 100.0    16.3  46.2  0.4   35.4 1.7                                    __________________________________________________________________________

Dehydrochlorination of 1,1,1-Trichloroethane

1,1,1-trichloroethane (1,1,1-TCA) was converted using the process of Example 1. 100% conversion to product was obtained at GHSV of 1260 hr⁻¹ at 450° C. using a nickel containing ZSM-5 catalyst (20% by weight nickel). Aromatic compound yield was steady over a period of 20 hrs at about 40%. Olefin yield was low, being less than 5% after 20 hrs onstream. Paraffin yield ranged from 50-60%. There was no chlorine present in the products. Conversion of starting material was 100%.

EXAMPLE 5

This example illustrates removal of two chlorine atoms from an aliphatic hydrocarbon using a nickel-containing zeolite catalyst.

Conversion of Methylene Chloride

Methylene chloride was converted under the same conditions described in Example 2. Results are shown in Table V. A ZSM-5 catalyst containing 10% nickel was used. Small amounts of methyl chloride, less than 4%, were consistently obtained. As shown in Table XV, it is possible to adjust reaction conditions to essentially eliminate CH₃ Cl formation in CH₂ Cl₂ hydrodechlorination. FIG. 3 shows conversion and product distribution for methylene chloride in the presence of hydrogen and methanol.

                                      TABLE V                                      __________________________________________________________________________     Ni/H-ZSM-5/Al.sub.2 O.sub.3 Catalyzed Conversion of CH.sub.2 Cl.sub.2          __________________________________________________________________________     Feed:                                                                          CH.sub.2 Cl.sub.2 (ml/min)                                                                2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3                                     H.sub.2 (ml/min)                                                                          12.0                                                                               12.0                                                                               12.0                                                                               12.0                                                                               12.0                                                                               12.0                                                                               12.0                                                                               12.0                                    Time on-stream (min)                                                                      70  140 220 290 335 370 455 495                                     Temperature (°C.)                                                                  450 450 450 450 450 450 450 550                                     WHSV (1/hr).sup.1                                                                         1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4                                     Conversion (%)                                                                            100 100 100 100 100 100 100 100                                     Methyl Chloride (%)                                                                       3.6 2.0 4.2 3.9 3.9 3.9 3.8 3.8                                     Hydrocarbon Distribution (%).sup.2                                             Olefins                                                                        C.sub.2    2.2 2.5 4.2 3.8 4.6 4.1 4.8 4.5                                     C.sub.3    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                     C.sub.4+   0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                     C.sub.5    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                     Selectivity (%)                                                                           2.2 2.5 4.2 3.8 4.6 4.1 4.8 4.5                                     Paraffins                                                                      C.sub.1    55.4                                                                               61.0                                                                               58.2                                                                               55.3                                                                               59.4                                                                               54.3                                                                               58.7                                                                               56.7                                    C.sub.2    3.8 2.7 3.1 2.5 3.0 2.6 2.8 2.6                                     C.sub.3    0.3 0.2 0.8 0.8 0.9 1.0 1.1 0.9                                     C.sub.4+   0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                     C.sub.5    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                     Selectivity (%)                                                                           59.5                                                                               63.9                                                                               62.1                                                                               58.6                                                                               63.3                                                                               57.9                                                                               62.6                                                                               62.4                                    Aromatics                                                                      Benzene    5.7 3.8 3.0 2.5 2.4 2.3 2.0 1.9                                     Toluene    15.3                                                                               13.0                                                                               11.4                                                                               10.9                                                                               10.0                                                                               10.0                                                                               8.8 7.9                                     Ethylbenzene                                                                              0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                     Xylenes    9.7 11.3                                                                               10.5                                                                               14.6                                                                               10.4                                                                               15.4                                                                               11.9                                                                               13.7                                    Ethyltoluene                                                                              1.0 1.2 1.4 2.3 2.7 2.9 3.3 2.8                                     Trimethylbenzene                                                                          2.6 2.1 2.8 3.0 2.2 2.9 2.3 2.6                                     Fused-ring aromatics                                                                      0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                     Selectivity (%)                                                                           34.3                                                                               31.4                                                                               29.1                                                                               33.3                                                                               27.7                                                                               33.5                                                                               28.3                                                                               28.9                                    __________________________________________________________________________      1. 10% Ni/HZSM-5/Al.sub.2 O.sub.3 (H-ZSM-5/Al.sub.2 O.sub.3 = 40:60,           HZSM-5 was treated with HNO.sub.3 solution): Catalyst mass: 0.400 g.           2. Percentage based on carbon number of compound.                        

EXAMPLE 6

This examples illustrates the effect of percent nickel loading in the zeolite on complete removal of chlorine from 1,1,1-trichloroethane.

Effect of Nickel Loading of ZSM-5

Table VI shows results of conversion of 1,1,1-TCA in the presence of hydrogen at 4500C over a 3% nickel-loaded ZSM-5 catalyst. Complete chlorine stripping was obtained initially but after approximately 280 minutes onstream, an initial chlorohydrocarbon product (vinyl chloride) was observed and chlorohydrocarbons increased with continued reaction. Table VII illustrates that at 1% nickel loading significant chlorohydrocarbon product was obtained after only 63 minutes time onstream in the conversion of 1,1,2-TCA. At higher nickel loadings, as shown in Tables I and III, no chlorinated hydrocarbon products were observed under the same conditions of reaction.

EXAMPLE 7

This example illustrates the high catalytic activity of the Ni/ZSM-5/Al₂ O₃ catalyst developed as shown by complete dechlorination of 1,1,1-TCA over a wide range of contact times between the reactant and the catalyst.

Effect of High Space Velocities on 1,1,1-TCA Conversion

The effect of space velocities ranging from 17827 to 608 hr⁻¹ GHSV on 1,1,1-TCA conversion are shown in Table VIII. Although the accelerated flows decreased the contact time between the reactant and catalyst, the reactant WHSV remained about 0.65⁻¹, the same observed with the lesser flow rates used in previous examples. As illustrated by these results, it was clearly possible to obtain complete dechlorination of the 1,1,1-TCA reactant over a wide range of contact times between the reactant and the Ni/ZSM-5/Al₂ O₃ catalyst.

                                      TABLE VI                                     __________________________________________________________________________     1,1,1 Trichloroethane/H.sub.2 over Ni(3%)/HZSM5/Al.sub.2 O.sub.3 at            450° C..sup.a                                                           __________________________________________________________________________     TOS (min):  76  133 191 283 339 397 508 635 717                                Conv (%):   100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                              Product Distribution                                                           TCA         0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                1,1 DCE.sup.1                                                                              0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.5 1.0                                Vinylchloride                                                                              0.0 0.0 0.0 0.1 0.2 0.3 0.6 1.0 1.3                                Other chloro compounds                                                                     0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                Hydrocarbon 100.0                                                                              100.0                                                                              100.0                                                                              99.9                                                                               99.8                                                                               99.7                                                                               99.3                                                                               98.5                                                                               97.7                               Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2     6.6 11.1                                                                               12.1                                                                               10.1                                                                               12.9                                                                               12.3                                                                               14.6                                                                               14.7                                                                               17.7                               C.sub.3     4.2 6.2 7.9 7.5 9.3 8.8 10.5                                                                               11.1                                                                               12.8                               1 + i-C.sub.4                                                                              0.2 0.5 0.5 0.6 0.8 0.8 1.2 1.5 1.9                                2-C.sub.4   0.3 0.6 0.7 0.6 0.9 0.9 1.1 1.3 1.7                                C.sub.5+    0.1 0.1 0.1 0.0 0.1 0.1 0.5 0.5 0.6                                Selectivity:                                                                               11.4                                                                               18.5                                                                               21.3                                                                               18.8                                                                               24.0                                                                               23.1                                                                               27.9                                                                               29.1                                                                               34.7                               Paraffins                                                                      C.sub.1     2.6 3.8 4.1 3.5 4.5 4.4 5.5 6.2 7.7                                C.sub.2     0.6 0.9 1.0 1.0 1.0 1.0 1.2 1.7 2.1                                C.sub.3     0.3 0.1 0.5 0.1 0.1 0.1 0.1 0.1 0.2                                C.sub.4+    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                Selectivity:                                                                               3.5 4.8 5.6 4.6 5.6 5.5 6.8 8.0 10.0                               Aromatics                                                                      Benzene     6.4 7.6 7.4 6.7 6.7 6.3 6.1 5.8 6.2                                Toluene     14.8                                                                               17.6                                                                               17.6                                                                               16.8                                                                               16.2                                                                               15.8                                                                               15.4                                                                               15.1                                                                               16.3                               C.sub.8     9.6 11.2                                                                               11.6                                                                               11.8                                                                               11.0                                                                               11.2                                                                               11.5                                                                               12.2                                                                               11.5                               C.sub.9     3.2 3.0 3.4 4.5 4.3 5.0 5.1 5.9 4.6                                C.sub.10    18.1                                                                               13.1                                                                               11.4                                                                               14.1                                                                               12.2                                                                               12.6                                                                               11.2                                                                               11.1                                                                               10.8                               C.sub.11    33.0                                                                               24.2                                                                               21.7                                                                               22.7                                                                               20.0                                                                               20.5                                                                               16.0                                                                               12.8                                                                               5.9                                Selectivity 85.1                                                                               76.7                                                                               73.1                                                                               76.6                                                                               70.4                                                                               71.4                                                                               65.3                                                                               62.9                                                                               55.3                               __________________________________________________________________________      .sup.a TCA = 4.3 mg/min, H.sub.2 = 5 ml/min, N.sub.2 = 25 ml/min, WHSV =       0.65 hr.sup.-1, catalyst = 400 mg, DCE = dichloroethylene.               

                  TABLE VII                                                        ______________________________________                                         1,1,2 Trichloroethane/H.sub.2 over Ni(1%)/HZSM5/Al.sub.2 O.sub.3 at            450° C..sup.a                                                           ______________________________________                                         TOS (min):   63      107     145   275   376                                   Conv. (%):   100.0   100.0   100.0 100.0 100.0                                 Product Distribution                                                           TCA          0.0     0.0     0.0   0.0   0.0                                   1,1 DCE.sup.a                                                                               1.0     7.1     8.8   12.3  12.5                                  Vinylchloride                                                                               0.0     2.6     3.4   4.9   5.1                                   Other Chloro Com-                                                                           0.0     0.0     0.0   0.0   0.0                                   pounds                                                                         Hydrocarbon  99.0    90.3    87.8  82.8  82.4                                  Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2      1.5     9.0     11.1  12.9  15.9                                  C.sub.3      0.5     9.4     11.4  12.1  12.6                                  1 + i-C.sub.4                                                                               0.0     1.4     2.1   2.0   2.8                                   2-C.sub.4    0.0     1.4     2.3   1.8   3.2                                   C.sub.5+     0.0     0.3     0.9   2.5   3.6                                   Selectivity: 2.0     21.5    27.8  31.3  38.1                                  Paraffins                                                                      C.sub.1      1.4     2.6     3.4   4.4   5.0                                   C.sub.2      0.1     0.6     0.7   1.3   1.4                                   C.sub.3      0.2     0.2     0.2   0.2   0.2                                   C.sub.4+     0.0     0.0     0.0   0.0   0.0                                   Selectivity: 1.7     3.4     4.3   5.9   6.6                                   Aromatics                                                                      Benzene      1.7     6.5     5.9   4.8   4.5                                   Toluene      6.7     16.3    15.9  13.5  12.3                                  C.sub.8      8.7     13.5    14.5  13.6  12.4                                  C.sub.9      36.9    8.0     9.1   9.1   8.3                                   C.sub.10     14.1    12.0    7.2   10.4  9.1                                   C.sub.11     27.5    18.6    15.3  11.4  8.2                                   Selectivity: 95.6    74.9    67.9  62.8  54.8                                  ______________________________________                                          .sup.a TCA = 4.3 mg/min, H.sub.2 = 5 ml/min, N.sub.2 = 25 ml/min, WHSV =       0.65 hr.sup.-1, catalyst = 400 mg, DCE = dichloroethylene.               

                                      TABLE VIII                                   __________________________________________________________________________     Accelerates Flow Rate Through Catalyst                                         1,1,1 Trichloroethane/H.sub.2 over Ni(5%)/HZSM5/Al.sub.2 O.sub.3 at            450° C..sup.a                                                           __________________________________________________________________________     H.sub.2 (ml/min):                                                                      5.0   5.0   5.0  5.0  5.0  5.0                                         He (ml/min):                                                                           164   95    41.4 16.8 6.1  0.0                                         GHSV (hr.sup.-1):                                                                      17827 10582 4954 2371 1247 608                                         Conv (%):                                                                              100.0 100.0 100.0                                                                               100.0                                                                               100.0                                                                               100.0                                       Product Distribution                                                           Chlorinated                                                                            0.0   0.0   0.0  0.0  0.0  0.0                                         Compounds                                                                      Hydrocarbon                                                                            100.0 100.0 100.0                                                                               100.0                                                                               100.0                                                                               100.0                                       Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2 7.5   10.4  10.4 10.4 7.3  4.7                                         C.sub.3 5.0   7.4   6.9  7.5  6.2  4.1                                         1 + i-C.sub.4                                                                          0.0   0.0   0.0  0.4  0.7  0.8                                         2-C.sub.4                                                                              0.0   0.0   0.0  0.5  1.4  1.4                                         Selectivity:                                                                           12.5  17.8  17.3 18.8 15.6 11.0                                        Paraffins                                                                      C.sub.1 5.9   6.0   4.7  4.6  5.0  6.0                                         C.sub.2 0.8   0.8   1.0  0.7  1.5  2.3                                         C.sub.3 0.0   0.0   0.0  2.2  4.2  7.5                                         i-C.sub.4                                                                              0.0   0.0   0.0  0.0  0.4  1.9                                         n-C.sub.4                                                                              0.0   0.0   0.0  0.0  0.4  1.2                                         Selectivity:                                                                           6.7   6.8   5.7  7.5  11.5 18.9                                        C.sub.5+ -                                                                             0.0   0.0   0.0  0.4  1.5  1.9                                         Aliphatics                                                                     Aromatics                                                                      Benzene 10.9  9.9   8.7  8.1  7.8  7.3                                         Toluene 20.0  21.2  21.2 20.8 21.2 21.5                                        C.sub.8 6.0   10.8  12.8 13.7 16.8 18.3                                        C.sub.9 0.0   0.0   3.9  3.1  3.8  4.6                                         C.sub.10                                                                               25.6  16.8  12.7 9.9  7.3  5.4                                         C.sub.11+                                                                              18.3  16.7  17.7 17.7 14.5 11.1                                        Selectivity:                                                                           80.8  75.4  77.0 73.3 71.4 68.2                                        __________________________________________________________________________      .sup.a catalyst = 400 mg, TCA = 4.3 mg/min.                              

EXAMPLE 8

The following are examples of ineffective catalysts with respect to achieving continuous complete dechlorination of polychlorinated reactants as demonstrated with 1,1,1-TCA. These catalysts include pure H-ZSM-5, pure Al₂ O₃ and a combined Ni/Al₂ O₃ catalyst.

Effect of Catalyst on 1,1,1-TCA Conversion

Table IX shows that the H-ZSM-5 catalyst underwent rapid deactivation with the initial product mix consisting basically of 1,1-dichloroethylene (54%) and hydrocarbons (44%). With continued time onstream, the hydrocarbon yield dropped rapidly and 1,1-dichloroethylene represented 95% of the products after only 258 minutes time onstream.

Table X shows that pure Al₂ O₃ catalyst hydrodechlorinated TCA but only to the extent of forming primarily dichloroethylene. With pure Al₂ O₃ catalyst, the initial low yield of hydrocarbons (16%) decreased rapidly with time onstream.

Table XI shows that whereas a combined Ni/Al₂ O₃ catalyst exhibited good initial activity for complete chlorine stripping of TCA, this activity lasted only about 1 hr. Subsequently, catalyst deactivation occurred, leading to a decrease in hydrocarbon formation from 100% to 8% after 323 minutes of time onstream.

                  TABLE IX                                                         ______________________________________                                         No Ni                                                                          1,1,1 Trichloroethane/H.sub.2 over H-ZSM-5 at 450° C..sup.a             ______________________________________                                         TOS (min)                                                                               10      38      80    150   209   258                                 Conv. (%)                                                                               100.0   100.0   100.0 100.0 100.0 100.0                               Product Distribution                                                           1,1 dichloro-                                                                           54.1    64.7    86.3  91.5  93.5  94.7                                ethylene                                                                       cis-1,2 di-                                                                             0.5     0.9     0.3   0.1   0.1   0.1                                 chloro-                                                                        ethylene                                                                       trans-1,2                                                                               0.0     0.3     0.0   0.0   0.0   0.0                                 dichloro-                                                                      ethylene                                                                       Vinylchloride                                                                           0.0     1.9     1.9   1.5   1.3   1.4                                 Other chloro                                                                            1.3     0.5     0.8   0.5   0.4   0.3                                 compounds                                                                      Hydro-   44.1    31.7    10.7  6.4   4.7   3.5                                 carbons                                                                        ______________________________________                                          .sup.a TCA = 4.3 mg/min, H.sub.2 = 5 ml/min, N.sub.2 = 25 ml/min, WHSV =       0.65 hr.sup.-1, catalyst = 400 mg.                                       

                  TABLE X                                                          ______________________________________                                         Pure Al.sub.2 O.sub.3 as catalyst. (No Ni or ZSM5)                             1,1,1 Trichloroethane/H.sub.2 over Al.sub.2 O.sub.3 at 450°             C..sup.a                                                                       ______________________________________                                         TOS (min)    20      45      82    115   179                                   Conv. (%)    100.0   100.0   100.0 100.0 100.0                                 Product Distribution                                                           1,1 dichloroethylene                                                                        83.2    89.3    92.1  92.2  89.1                                  cis-1,2 dichloro-                                                                           0.0     0.0     0.0   0.0   0.0                                   ethylene                                                                       trans-1,2 dichloro-                                                                         0.0     0.0     0.0   0.0   0.0                                   ethylene                                                                       Vinylchloride                                                                               0.2     0.3     0.8   1.6   3.7                                   Other chloro 0.0     0.0     0.1   0.8   3.2                                   compounds                                                                      Hydrocarbons 16.6    10.4    7.0   5.4   4.0                                   ______________________________________                                          .sup.a TCA = 4.3 mg/min, H.sub.2 = 5 ml/min, N.sub.2 = 25 ml/min, WHSV =       0.65 hr.sup.-1, catalyst = 400 mg.                                       

                                      TABLE XI                                     __________________________________________________________________________     No ZSM-5                                                                       1,1,1 Trichloroethane/H.sub.2 over Ni(13%)/Al.sub.2 O.sub.3 at                 450° C..sup.a                                                           __________________________________________________________________________     TOS (min):   14  61  98  178 246 299 323                                       Conv. (%)    100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              98.4                                                                               94.2                                      Product Distribution                                                           TCA          0.0 0.0 0.0 0.0 0.0 1.6 5.8                                       1,1 dichloroethylene                                                                        0.0 0.1 6.0 26.1                                                                               32.8                                                                               29.4                                                                               30.3                                      cis-1,2 dichloroethylene                                                                    0.0 0.0 0.0 0.0 16.4                                                                               32.1                                                                               33.5                                      trans-1,2    0.0 0.0 0.0 0.0 0.0 0.0 0.0                                       dichloroethylene                                                               Vinylchloride                                                                               0.0 0.0 0.3 2.9 1.5 1.3 1.3                                       Other Chloro Compounds                                                                      0.0 10.2                                                                               23.0                                                                               36.2                                                                               34.6                                                                               23.0                                                                               20.4                                      Hydrocarbons 100.0                                                                              89.7                                                                               70.7                                                                               34.8                                                                               14.7                                                                               12.6                                                                               8.7                                       __________________________________________________________________________      .sup.a TCA = 4.3 mg/min, H.sub.2 = 5 ml/min, N.sub.2 = 25 ml/min, WHSV =       0.65 hr.sup.-1, catalyst = 400 mg, DCE = dichloroethylene.               

EXAMPLE 9 Effect of Temperature on Conversion Yields

Table XII shows the effect of reaction temperature on the conversion process for trichloroethylene. In order to achievecomplete conversion of TCE and negligible chlorinated hydrocarbon products, a minimum reaction temperature of 350° C. or higher is required for the particular WHSV used in these experiments.

Product distribution as a function of reaction temperature in the conversion of 1,1,2-TCA is shown in FIG. 2 under conditions of a high ratio of [H₂ ] to [TCA] of 120:1. Product distribution is affected by the addition of water to the TCA/H₂ feedstream. There is an exceptionally high yield of aromatic products, at temperatures below 400° C., exceeding 70% when the reaction is run at 350° C. at lower of [H₂ ] to [TCA] as shown in Table II.

EXAMPLE 10

The following example illustrates the long-term catalytic stability and effectiveness of the Ni/ZSM-5/Al₂ O₃ catalyst in promoting complete hydrodechlorination of polyhalogenated reactants. In this run, conducted over an elapsed time of 162 continuous hours, the reaction temperature was cycled over the range of 425° C. to 300° C. Additionally, the reactant ratio of 1,1,2-TCA to H₂ was varied. Good reproducibility of product distributions was noted even after long periods of on-stream conversion. The conversions were carried out at relatively high molar ratios of H₂ to 1,1,2-TCA thus limiting the yield of aromatics observed among the products. The reaction was terminated after 162 consecutive hours of conversion at which point the catalyst was still providing loot dechlorination of the starting 1,1,2-TCA reactant. The results from this extended conversion reaction are summarized in Table XIII.

                  TABLE XII                                                        ______________________________________                                         Trichloroethylene over Ni(10%)/H-ZSM-5(1)                                      ______________________________________                                         Temperature (°C.):                                                                   250     300     350   400   450                                   Conv. (%):   12.3    50.0    98.4  100.0 100.0                                 Product Distribution                                                           Chlorinated  14.5    2.1     0.2   0.1   0.0                                   Hydrocarbon                                                                    Hydrocarbon  85.5    97.9    99.8  99.9  100.0                                 Hydrocarbon Distribution                                                       Acetylene    9.2     2.7     0.5   1.1   2.7                                   C.sub.5+     0.6     1.0     0.3   0.4   0.9                                   Aliphatics                                                                     Olefins                                                                        C.sub.2      15.3    14.6    11.3  15.0  20.2                                  C.sub.3      0.5     0.3     0.2   0.4   0.4                                   C.sub.4      0.0     0.0     0.0   0.0   0.9                                   Selectivity: 15.8    14.9    11.5  15.4  20.6                                  Paraffins                                                                      C.sub.2      18.5    8.7     5.8   10.7  13.3                                  C.sub.3      16.2    25.3    28.3  30.8  14.1                                  i-butane     8.8     6.7     3.6   2.6   0.6                                   n-butane     6.8     5.1     2.3   1.6   0.4                                   Selectivity: 75.3    45.8    40.0  45.7  28.4                                  Aromatics                                                                      Benzene      0.0     1.7     7.8   10.3  17.9                                  Toluene      0.8     6.3     18.5  14.5  17.9                                  C.sub.8      2.3     9.9     12.6  6.0   3.6                                   C.sub.9      3.3     6.1     2.9   1.0   0.7                                   C.sub.10+    3.2     11.6    5.9   5.6   6.1                                   Selectivity: 9.6     35.6    47.7  37.4  47.4                                  ______________________________________                                          Condition: TCE = 4.7 mg/min, H.sub.2 = 12 ml/min, WHSV = 0.70 hr.sup.-1,       catalyst = 400 mg.                                                             Percentage based on carbon number and 1 hr on stream.                    

                                      TABLE XIII                                   __________________________________________________________________________     1,1,1 Trichloroethane/H.sub.2 over Ni(10%)/HZSM5 at 450° C..sup.a       __________________________________________________________________________     TOS (min):  30  71  124 180 233 329 385 441 481                                Conv (%):   100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                              Product Distribution                                                           TCA         0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                1,1 DCE.sup.1                                                                              0.0 0.0 0.0 0.0 0.0 0.0 0.3 8.9 26.1                               Vinylchloride                                                                              0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.4 6.8                                Other chloro compounds                                                                     0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 2.4                                Hydrocarbon 100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              99.7                                                                               89.4                                                                               64.7                               Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2     6.3 8.9 10.1                                                                               10.5                                                                               11.5                                                                               12.9                                                                               13.8                                                                               15.1                                                                               17.6                               C.sub.3     2.5 3.7 4.5 4.8 5.5 6.8 6.7 10.0                                                                               11.0                               1 + i-C.sub.4                                                                              0.0 0.2 0.0 0.1 0.5 0.5 0.5 0.8 1.4                                2-C.sub.4   0.1 0.3 0.1 0.1 0.7 0.5 0.6 0.9 1.5                                C.sub.5+    0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.5 0.4                                Selectivity:                                                                               8.9 13.1                                                                               14.7                                                                               15.5                                                                               18.2                                                                               20.7                                                                               21.8                                                                               27.3                                                                               31.9                               Paraffins                                                                      C.sub.1     12.5                                                                               14.7                                                                               16.4                                                                               15.6                                                                               17.8                                                                               19.5                                                                               20.9                                                                               23.0                                                                               23.7                               C.sub.2     1.9 1.7 1.8 1.6 1.7 1.7 1.6 1.9 2.4                                C.sub.3     2.0 2.2 2.1 1.9 1.8 1.2 0.1 0.6 0.7                                C.sub.4+    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.6                                Selectivity:                                                                               16.4                                                                               18.6                                                                               20.3                                                                               19.1                                                                               21.3                                                                               22.4                                                                               22.6                                                                               25.5                                                                               27.4                               Aromatics                                                                      Benzene     11.5                                                                               10.6                                                                               10.1                                                                               9.7 9.1 8.3 8.1 6.8 6.2                                Toluene     18.4                                                                               17.5                                                                               17.1                                                                               17.0                                                                               16.3                                                                               15.7                                                                               14.9                                                                               13.5                                                                               12.4                               C.sub.8     7.9 7.7 7.7 8.0 7.8 7.6 7.4 7.9 7.9                                C.sub.9     1.1 1.1 1.3 1.7 1.9 1.5 3.3 3.3 3.6                                C.sub.10    15.3                                                                               12.6                                                                               11.4                                                                               10.9                                                                               9.5 8.8 8.5 6.3 5.0                                C.sub.11+   20.5                                                                               18.8                                                                               17.4                                                                               18.1                                                                               15.9                                                                               15.0                                                                               13.4                                                                               9.4 5.6                                Selectivity:                                                                               74.7                                                                               68.3                                                                               65.0                                                                               65.4                                                                               60.5                                                                               56.9                                                                               55.6                                                                               47.2                                                                               40.7                               __________________________________________________________________________      .sup.a TCA = 4.3 mg/min, H.sub.2 = 5 ml/min, N.sub.2 = 25 ml/min, WHSV =       0.65 hr.sup.-1, catalyst = 400 mg, DCE = dichlorethylene.                

EXAMPLE 11

The following examples illustrate that the hydrodechlorination process developed continued to operate effectively even when conversions of the polyhalogenated reactants were carried out in the presence of added reactants such as water and methanol.

Table XIV represents the reaction carried out using a reactant mixture of 1,1,1-TCA, water and hydrogen. Complete dechlorination was obtained with respect to reaction products. The product distribution was similar to that observed with TCA/H₂ mixtures (compare Table I), indicating that the presence of H₂ O had relatively little effect on product distributions when H₂ was present in sufficient concentration.

Tables XV and XVI show data obtained in reactions of equimolar amounts of methylene chloride and methanol in the presence of hydrogen. The conversion was initiated at 450° C. and carried out for approximately 27 hrs at that temperature (Table XV). Subsequently, the temperature was lowered at this point, with the conversion efficiency remaining near 100%. Essentially complete chlorine atom stripping was observed at both temperatures with only minor amounts of methyl chloride noted. The product distribution for CH₂ Cl₂ /CH₃ OH/H₂ at 450° C. (Table XV) was similar to that observed with CH₂ Cl₂ /H₂ reactant mixtures at 450° C. (Table XVI). Decreasing the conversion temperature to 400° C. resulted in a sharp change in product distribution for this system (compare data in Tables XV and XVI). At 400° C., a much higher aromatic yield was obtained (particularly for C₉ compounds) with a sharp decrease in methane yield.

Table XVII illustrates conversion of CH₂ Cl₂ with added CH₃ OH in which the reaction was initiated at 450° C. with subsequent lowering of the temperature to 350° C. Complete conversion of CH₂ Cl₂ was obtained with essentially no chlorohydrocarbon byproducts produced. FIG. 3 shows product distribution with time onstream.

                                      TABLE XIV                                    __________________________________________________________________________     1,1,1 Trichloroethane/H.sub.2 O/H.sub.2 over Ni(20%)/HZSM5 + Al.sub.2          O.sub.3 at 450° C..sup.a                                                __________________________________________________________________________     TOS (min):   60  145 183 255 312 374 430 483                                   Conv (%):    100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                 Product Distribution                                                           Chlorinated Hydrocarbon                                                                     0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                   Hydrocarbon  100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                 Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2      0.7 1.4 1.6 4.2 4.8 6.4 11.5                                                                               14.9                                  C.sub.3      0.5 0.8 1.0 4.6 3.6 4.6 8.3 8.0                                   1 + i-C.sub.4                                                                               0.0 0.0 0.0 0.0 0.0 0.0 1.4 0.6                                   2-C.sub.4    0.0 0.0 0.0 0.0 0.0 0.0 1.5 0.7                                   Selectivity: 1.2 2.2 2.6 8.8 8.4 11.0                                                                               22.7                                                                               24.2                                  Paraffins                                                                      C.sub.1      35.0                                                                               27.5                                                                               30.2                                                                               25.0                                                                               23.0                                                                               21.9                                                                               17.7                                                                               17.6                                  C.sub.2      5.4 5.0 5.1 5.0 4.0 4.0 3.6 3.7                                   C.sub.3      0.7 0.3 0.3 0.0 0.0 0.0 0.2 0.0                                   i-C.sub.4    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                   n-C.sub.4    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                   Selectivity: 41.1                                                                               32.8                                                                               35.6                                                                               30.0                                                                               27.0                                                                               25.9                                                                               21.5                                                                               21.3                                  C.sub.5+ - Aliphatics                                                                       0.0 0.7 1.1 1.2 4.0 1.8 1.5 0.6                                   Aromatics                                                                      Benzene      14.7                                                                               13.8                                                                               12.9                                                                               11.6                                                                               9.9 8.5 7.5 8.7                                   Toluene      19.9                                                                               20.2                                                                               18.7                                                                               17.6                                                                               14.8                                                                               13.3                                                                               13.0                                                                               14.3                                  C.sub.8      6.9 7.4 6.9 6.5 5.9 5.6 6.0 6.6                                   C.sub.9      0.0 0.0 0.0 0.0 0.0 0.0 1.6 1.5                                   C.sub.10+    16.2                                                                               22.9                                                                               22.2                                                                               24.3                                                                               30.0                                                                               33.9                                                                               26.2                                                                               22.8                                  Selectivity: 57.7                                                                               64.3                                                                               60.7                                                                               60.0                                                                               60.6                                                                               61.3                                                                               54.3                                                                               53.9                                  __________________________________________________________________________      TCA = 4.3 mg/min, H.sub.2 = 5 ml/min, H.sub.2 O = 2.9 mg/min, N.sub.2 = 2      ml/min, WHSV = 0.65 hr.sup.-1 Catalyst = 400 mg.                         

                                      TABLE XV                                     __________________________________________________________________________     Ni/H-ZSM-5/Al.sub.2 O.sub.3 Catalyzed Conversion of CH.sub.3 OH/CH.sub.2       Cl.sub.2                                                                       __________________________________________________________________________     Feed:                                                                          CH.sub.3 OH (ml/min)                                                                      2.0 2.0 2.0 2.0 2.0 2.0  2.0  2.0                                   CH.sub.2 Cl.sub.2 (ml/min)                                                                2.0 2.0 2.0 2.0 2.0 2.0  2.0  2.0                                   H.sub.2 (ml/min)                                                                          12.0                                                                               12.0                                                                               12.0                                                                               12.0                                                                               12.0                                                                               12.0 12.0 12.0                                  Time on-stream (min)                                                                      310 350 420 460 505 1505 1550 1600                                  Temperature (°C.)                                                                  450 450 450 450 450 450  450  450                                   WHSV (1/hr).sup.1                                                                         2.7 2.7 2.7 2.7 2.7 2.7  2.7  2.7                                   Conversion (%).sup.2                                                                      100 100 100 100 100 99.8 99.8 99.7                                  Methyl Chloride (%)                                                                       0.0 0.0 0.0 0.0 0.0 0.9  0.9  0.8                                   Methanol (%)                                                                              1.1 0.0 0.3 0.0 0.0 0.0  0.0  0.0                                   Hydrocarbon Distribution (%).sup.3                                             Olefins                                                                        C.sub.2    1.4 1.6 1.4 1.8 1.7 3.5  3.2  3.0                                   C.sub.3    0.0 0.0 0.0 0.0 0.0 0.0  0.0  0.0                                   C.sub.4+   0.0 0.0 0.0 0.0 0.0 0.1  0.1  0.1                                   C.sub.5    0.0 0.0 0.0 0.0 0.0 0.0  0.0  0.0                                   Selectivity (%)                                                                           1.4 1.6 1.4 1.8 1.7 3.6  3.3  3.1                                   Paraffins                                                                      C.sub.1    67.9                                                                               74.7                                                                               81.4                                                                               80.2                                                                               80.2                                                                               75.2 76.8 77.2                                  C.sub.2    0.9 1.1 1.3 1.4 1.3 2.2  2.2  2.3                                   C.sub.3    0.0 0.0 0.0 0.0 0.0 1.0  0.9  0.8                                   C.sub.4+   0.0 0.0 0.0 0.0 0.0 0.0  0.0  0.0                                   C.sub.5    0.0 0.0 0.0 0.0 0.0 0.0  0.0  0.0                                   Selectivity (%)                                                                           68.8                                                                               75.8                                                                               82.7                                                                               81.6                                                                               81.5                                                                               78.4 79.9 80.3                                  Aromatics                                                                      Benzene    0.7 0.8 1.1 1.0 1.0 1.4  1.6  1.9                                   Toluene    8.3 4.2 4.6 4.4 4.4 4.4  4.2  4.5                                   Ethylbenzene                                                                              0.0 0.0 0.0 0.0 0.0 0.0  0.0  0.0                                   Xylenes    10.5                                                                               7.2 5.9 6.4 6.7 7.2  6.4  6.0                                   Ethyltoluene                                                                              1.6 1.3 0.9 1.0 1.1 0.9  0.8  0.6                                   Trimethylbenzene                                                                          4.9 3.7 2.5 2.9 3.0 2.5  2.0  1.5                                   Fused-ring aromatics                                                                      2.7 5.4 0.9 0.8 0.6 0.7  0.6  1.0                                   Selectivity (%)                                                                           28.7                                                                               22.6                                                                               15.9                                                                               16.5                                                                               16.8                                                                               16.7 15.6 15.5                                  __________________________________________________________________________      .sup.1 10% Ni/HZSM-5/Al.sub.2 O.sub.3 (H-ZSM-5/Al.sub.2 O.sub.3 = 40:60,       HZSM-5 was treated with HNO.sub.3 solution): Catalyst mass: 0.600 g. WHSV      calculated from weight of MeOH + MeCl.sub.2 in flow.                           .sup.2 Percent conversion indicates conversion of Methylene Chloride.          .sup.3 Percentage based on carbon number of compound.                    

                  TABLE XVI                                                        ______________________________________                                         Ni/H-ZSM-5/Al.sub.2 O.sub.3 Catalyzed Conversion of CH.sub.3 OH/CH.sub.2       Cl.sub.2                                                                       ______________________________________                                         Feed:                                                                          CH.sub.3 OH (ml/min)                                                                          2.0        2.0     2.0                                          CH.sub.2 Cl.sub.2 (ml/min)                                                                    2.0        2.0     2.0                                          H.sub.2 (ml/min)                                                                              12.0       12.0    12.0                                         Time on-stream (min).sup.1                                                                    0.0        50.0    90.0                                         Temperature (°C.).sup.1                                                                400        400     400                                          WHSV (1/hr).sup.2                                                                             2.7        2.7     2.7                                          Conversion (%).sup.3                                                                          98.9       98.9    99.2                                         Methyl Chloride (%)                                                                           1.3        1.3     1.0                                          Methanol (%)   0.4        0.4     0.4                                          Hydrocarbon Distribution (%).sup.4                                             Olefins                                                                        C.sub.2        3.5        3.7     3.4                                          C.sub.3        2.0        2.2     1.5                                          C.sub.4+       1.8        1.9     1.3                                          C.sub.5        0.0        0.0     0.0                                          Selectivity (%)                                                                               7.3        7.8     6.2                                          Paraffins                                                                      C.sub.1        38.5       39.1    49.0                                         C.sub.2        1.6        1.5     1.1                                          C.sub.3        4.1        4.1     2.7                                          C.sub.4+       1.5        1.5     1.2                                          C.sub.5        0.3        0.3     0.2                                          Selectivity (%)                                                                               46.0       46.5    54.2                                         Aromatics                                                                      Benzene        0.6        0.5     0.4                                          Toluene        2.4        2.2     1.8                                          Ethylbenzene   0.0        0.0     0.0                                          Xylenes        11.5       10.8    9.4                                          Ethyltoluene   5.5        5.3     4.7                                          Trimethylbenzene                                                                              19.7       20.0    17.7                                         Fused-ring aromatics                                                                          4.3        4.1     3.4                                          Selectivity (%)                                                                               44.0       42.9    37.4                                         ______________________________________                                           .sup.1 Time onstream at 400° C., then at 450° C. for 1600       minutes.                                                                       .sup.2 10% Ni/HZSM-5/Al.sub.2 O.sub.3 (H-ZSM-5/Al.sub.2 O.sub.3 = 40:60,       HZSM-5 was treated with HNO.sub.3 solution): Catalyst mass: 0.600 g. WHSV      calculated from weight of MeOH + MeCl.sub.2 in flow.                           .sup.3 Percent conversion indicates conversion of Methylene Chloride.          .sup.4 Percentage based on carbon number of compound.                    

                                      TABLE XVII                                   __________________________________________________________________________     Ni/H-ZSM-5/Al.sub.2 O.sub.3 Catalyzed Conversion of CH.sub.3 OH/CH.sub.2       Cl.sub.2                                                                       __________________________________________________________________________     Feed:                                                                          CH.sub.3 OH (ml/min)                                                                      1.3 1.3 1.3 1.3  1.3  1.3  1.3  1.3                                 CH.sub.2 Cl.sub.2 (ml/min)                                                                1.3 1.3 1.3 1.3  1.3  1.3  1.3  1.3                                 H.sub.2 (ml/min)                                                                          12.0                                                                               12.0                                                                               12.0                                                                               12.0 12.0 12.0 12.0 12.0                                Time on-stream (min)                                                                      60  115 175 215  270  320  365  410                                 Temperature (°C.)                                                                  450 450 350 350  350  350  350  350                                 WHSV (1/hr).sup.1                                                                         1.7 1.7 1.7 1.7  1.7  1.7  1.7  1.7                                 Conversion (%).sup.2                                                                      99.7                                                                               100 99.6                                                                               99.4 99.5 99.0 99.0 98.9                                Methyl Chloride (%)                                                                       1.7 0.6 1.4 0.0  2.6  0.0  0.0  0.0                                 Methanol (%)                                                                              0.0 0.0 0.0 0.2  0.0  0.4  0.5  0.5                                 Hydrocarbon Distribution (%).sup.3                                             Olefins                                                                        C.sub.2    0.7 3.4 0.4 1.2  0.5  0.9  1.3  0.7                                 C.sub.3    0.0 0.0 9.5 8.1  4.4  12.5 8.0  13.2                                C.sub.4+   0.1 0.0 1.2 1.0  1.3  1.5  1.3  1.8                                 C.sub.5    0.0 0.0 0.2 0.3  0.2  0.3  0.4  0.4                                 Selectivity (%)                                                                           0.8 3.4 11.3                                                                               10.6 6.4  15.2 11.0 16.1                                Paraffins                                                                      C.sub.1    55.1                                                                               74.9                                                                               16.8                                                                               12.9 14.6 13.3 10.4 12.5                                C.sub.2    1.2 0.0 1.3 0.9  1.2  1.3  0.7  1.2                                 C.sub.3    0.0 5.0 0.0 8.5  4.4  7.0  11.0 5.1                                 C.sub.4+   0.1 0.5 1.1 1.9  1.5  2.5  2.4  2.5                                 C.sub.5    0.0 0.0 0.0 0.0  0.0  0.0  0.0  0.0                                 Selectivity (%)                                                                           56.4                                                                               80.4                                                                               19.2                                                                               24.2 21.7 24.1 24.5 21.3                                Aromatics                                                                      Benzene    3.1 1.4 0.2 0.2  0.2  0.4  0.3  0.4                                 Toluene    10.5                                                                               4.4 1.8 1.3  1.0  2.0  1.6  2.2                                 Ethylbenzene                                                                              0.0 0.0 0.0 0.0  0.0  0.0  0.0  0.0                                 Xylenes    13.7                                                                               3.8 12.3                                                                               11.5 8.0  12.5 13.6 13.3                                Ethyltoluene                                                                              2.7 1.1 8.3 4.5  5.8  2.6  2.5  2.1                                 Trimethylbenzene                                                                          8.7 3.1 32.1                                                                               34.0 37.8 28.8 31.6 28.7                                Fused-ring aromatics                                                                      2.1 1.7 13.1                                                                               12.7 16.1 13.0 13.4 14.4                                Selectivity (%)                                                                           40.8                                                                               15.5                                                                               67.8                                                                               64.2 68.6 59.3 63.0 61.1                                __________________________________________________________________________     Feed:                                                                          CH.sub.3 OH (ml/min)                                                                      1.3 1.3 1.3 1.3  1.3  1.3  1.3  1.3                                 CH.sub.2 Cl.sub.2 (ml/min)                                                                1.3 1.3 1.3 1.3  1.3  1.3  1.3  1.3                                 H.sub.2 (ml/min)                                                                          12.0                                                                               12.0                                                                               12.0                                                                               12.0 12.0 12.0 12.0 12.0                                Time on-stream (min)                                                                      450 505 570 1500 1540 1580 1630 173                                                                            0                                   Temperature (°C.)                                                                  350 350 350 350  350  350  350  350                                 WHSV (1/hr).sup.1                                                                         1.7 1.7 1.7 1.7  1.7  1.7  1.7  1.7                                 Conversion (%).sup.2                                                                      100 100 100 100  100  100  100  98.9                                Methyl Chloride (%)                                                                       0.0 0.0 0.0 0.0  0.0  0.0  0.0  0.0                                 Methanol (%)                                                                              0.5 0.5 0.3 0.0  0.0  0.0  0.0  0.0                                 Hydrocarbon Distribution (%).sup.3                                             Olefins                                                                        C.sub.2    1.3 1.3 1.0 1.3  1.5  1.2  1.2  1.0                                 C.sub.3    8.7 9.6 7.1 11.2 11.9 10.9 9.8  8.5                                 C.sub.4+   1.7 2.3 2.1 2.6  1.8  2.4  2.1  2.1                                 C.sub.5    0.4 0.5 0.3 0.0  0.0  0.0  0.0  0.4                                 Selectivity (%)                                                                           12.1                                                                               13.7                                                                               10.5                                                                               15.1 15.2 14.5 13.1 12.0                                Paraffins                                                                      C.sub.1    11.0                                                                               11.9                                                                               14.1                                                                               29.2 28.9 25.8 26.3 25.7                                C.sub.2    0.9 0.9 0.9 0.0  0.0  0.0  0.0  0.0                                 C.sub.3    11.9                                                                               12.8                                                                               7.7 3.0  2.8  2.6  2.4  2.1                                 C.sub.4+   2.3 2.9 1.9 1.4  0.0  2.2  2.0  1.9                                 C.sub.5    0.2 0.2 0.2 0.0  0.0  0.0  0.0  0.0                                 Selectivity (%)                                                                           26.3                                                                               28.7                                                                               24.8                                                                               33.6 31.7 30.6 30.7 29.7                                Aromatics                                                                      Benzene    0.6 0.6 0.2 0.0  0.0  0.0  0.0  0.2                                 Toluene    2.0 2.5 1.5 1.7  1.4  1.4  1.2  1.2                                 Ethylbenzene                                                                              0.0 0.0 0.0 0.0  0.0  0.0  0.0  0.0                                 Xylenes    15.2                                                                               15.6                                                                               12.2                                                                               6.7  6.6  6.6  6.5  10.1                                Ethyltoluene                                                                              2.2 2.1 3.8 6.2  6.5  6.9  6.7  6.3                                 Trimethylbenzene                                                                          25.6                                                                               21.3                                                                               33.2                                                                               25.4 25.8 26.2 26.2 25.0                                Fused-ring aromatics                                                                      14.1                                                                               13.5                                                                               12.0                                                                               11.2 12.8 13.7 15.6 14.4                                Selectivity (%)                                                                           59.7                                                                               55.6                                                                               62.9                                                                               51.2 53.1 54.8 56.2 57.2                                __________________________________________________________________________      .sup.1 10% Ni/HZSM-5/Al.sub.2 O.sub.3 (H-ZSM-5/Al.sub.2 O.sub.3 = 40:60,       HZSM-5 was treated with HNO.sub.3 solution): Catalyst mass: 0.600 g. WHSV      calculated from weight of MeOH + MeCl.sub.2 in flow.                           .sup.2 Percent conversion indicates conversion of Methylene Chloride.          .sup.3 Percentage based on carbon number of compound.                    

EXAMPLE 12

This example illustrates the effectiveness of the Ni/H-ZSM-5/Al₂ O₃ catalyst in promoting hydrodebromination of bromine containing reactants. The results obtained using 1,2-dibromoethane as reactant are summarized in Table XVIII. Complete 100% conversion of the 1,2,-dibromoethane was maintained over the 8.5 hours of this experiment carried out at 425° C. No bromine-containing organic compounds were detected among the conversion products.

EXAMPLE 13

The following example illustrates the usefulness of the hydrodehalogenation catalyst in achieving complete dechlorination of a perchlorinated (i.e. completely chlorinated) organic reactant as demonstrated in the conversion of tetrachloroethylene. The results obtained in the hydrodechlorination of C₂ Cl₄ are shown in Table XIX for experiments conducted at 425° C. Over the 6 hour duration of this experiment, 100% conversion of the C₂ Cl₄ was achieved. No chlorinecontaining organic molecules were detected in the reaction products.

EXAMPLE 14

The following example illustrates a complete hydrodehalogenation of a fluorine containing compound. The compound is a typical example of perfluorochloro hydrocarbon similar to environmentally undesirable Freon-type compounds.

                                      TABLE XVIII                                  __________________________________________________________________________     1,2 Dibromoethane/H2 over 10% Ni/HZSM5/Al.sub.2 O.sub.3 at 425°         C..sup.a                                                                       __________________________________________________________________________     TOS (hr):    1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.5                                   Conv (%):    100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                 Product Distribution                                                           Brominated Hydrocarbons                                                                     0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0                                   Hydrocarbons 100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                                                              100.0                                 Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2      40.2                                                                               41.0                                                                               43.1                                                                               42.7                                                                               46.8                                                                               45.7                                                                               46.4                                                                               51.2                                  C.sub.3      13.9                                                                               14.9                                                                               15.8                                                                               15.6                                                                               17.0                                                                               15.9                                                                               16.1                                                                               16.9                                  1 + i-C.sub.4                                                                               1.3 1.3 1.5 1.3 0.9 0.8 0.8 0.8                                   2-C.sub.4    2.4 2.6 2.9 2.8 2.8 2.8 2.8 2.7                                   Selectivity  57.8                                                                               59.8                                                                               63.3                                                                               62.4                                                                               67.5                                                                               65.2                                                                               66.1                                                                               71.6                                  Paraffins                                                                      C.sub.1      3.0 3.0 3.2 3.4 3.6 3.1 2.7 2.5                                   C.sub.2      9.5 9.1 8.9 8.4 8.9 8.3 8.1 8.1                                   C.sub.3      4.4 4.5 4.6 4.6 4.5 4.1 4.0 3.8                                   i-C.sub.4    1.8 1.8 1.9 1.8 1.8 1.7 1.7 1.5                                   n-C.sub.4    1.1 1.1 1.1 1.1 1.1 0.8 0.8 0.9                                   Selectivity  19.8                                                                               19.5                                                                               19.7                                                                               19.3                                                                               19.9                                                                               18.0                                                                               17.3                                                                               16.8                                  Aliphatics   12.4                                                                               12.4                                                                               9.5 10.7                                                                               6.7 10.1                                                                               10.2                                                                               6.4                                   Aromatics                                                                      Benzene      1.6 1.6 1.1 1.5 1.1 1.1 1.2 0.7                                   Toluene      3.5 3.0 3.0 3.0 2.7 2.8 2.5 2.1                                   C.sub.8      3.2 3.1 3.0 2.9 2.8 2.6 2.4 2.2                                   C.sub.9+     1.8 0.4 0.4 0.2 0.3 0.2 0.3 0.2                                   Selectivity  10.1                                                                               8.1 7.5 7.6 6.9 6.7 6.4 5.2                                   __________________________________________________________________________      .sup.a catalyst = 200 mg, 12DBA = 5.0 mg/min, H2 = 15 ml/min, WHSV = 1.5       hr.sup.-1.                                                               

                  TABLE XIX                                                        ______________________________________                                         Tetrachloroethylene/H.sub.2 over 10% Ni/HZSM5/Al.sub.2 O.sub.3 at              425° C.                                                                 ______________________________________                                         TOS (hr):  2       3        4     5      6                                     Conv (%):  100.0   100.0    100.0 100.0  100.0                                 Product Distribution                                                           Chlorinated                                                                               0.0     0.0      0.0   0.0    0.0                                   Hydrocarbons                                                                   Hydrocarbons                                                                              100.0   100.0    100.0 100.0  100.0                                 Hydrocarbon Distribution                                                       Olefins                                                                        C.sub.2    0.2     0.4      1.4   4.7    10.0                                  C.sub.3    1.3     3.2      6.1   11.6   17.9                                  1 + i-C.sub.4                                                                             0.2     0.6      1.1   2.1    3.4                                   2-C.sub.4  0.0     0.9      1.5   2.5    3.7                                   Selectivity                                                                               1.7     5.1      10.1  20.9   35.0                                  Paraffins                                                                      C.sub.1    62.5    58.7     53.2  45.7   39.8                                  C.sub.2    16.1    16.2     16.3  13.7   9.4                                   C.sub.3    9.3     9.8      9.5   7.7    5.1                                   i-C.sub.4  0.9     0.9      1.2   1.1    0.7                                   n-C.sub.4  1.2     1.5      1.5   1.2    0.7                                   Selectivity                                                                               90.0    87.1     81.7  69.4   55.7                                  Aliphatics 0.1     0.2      0.6   1.3    1.3                                   Aromatics                                                                      Benzene    1.6     1.4      1.4   1.4    1.2                                   Toluene    4.8     4.3      4.3   4.3    4.3                                   C.sub.8    1.8     1.9      1.9   2.7    2.5                                   C.sub.9+   0.0     0.0      0.0   0.0    0.0                                   Selectivity                                                                               8.2     7.6      7.6   8.4    8.0                                   ______________________________________                                          .sup.a catalyst = 400 mg, C.sub.2 Cl.sub.4 = 5.3 mg/min, H.sub.2 = 30          ml/min, WHSV = 0.8 hr.sup.-1.                                            

Conversions of fluorine containing reactants were successfully carried out using the perhalogenated reactant trichlorotrifluoroethane, C₂ Cl₃ F₃, over a 10% Ni/ZSM-5/Al₂ O₃ catalyst. Complete conversion of the starting material was obtained and maintained over a 4 hour period at a reaction temperature of 425° C., a C₂ Cl₃ F₃ WHSV of 0.99 hr⁻¹ and a [H₂ ]/[C₂ Cl₃ F₃ ] ratio of 30 to 1. The hydrocarbon product distribution obtained consisted primarily of paraffins (90%) and olefins with virtually no aromatics observed.

RERERENCES

Bartholomew, C. H. and Farrauto, R. J., J. Catlysis, 45, 41 (1976).

Butler, S. A., Jurewicz, A. T. and Kaeding, W. W., U.S. Pat. No. 3,894,107, Jul. 8, 1975.

Chuang, S. C. and Bozzelli, J. W., Ind. Eng. Chem. Process. Des. Dev., 25, 321 (1986).

Deisen, R. W., U.S. Pat. No. 4,384,159, May 17, 1983.

Gokhberg, P. Ya, No, B. I., Zaidman, O. A. and Grinberg, S. B., Kinetica i Kataliz, 30, 1376 (1989).

Imamura, S. and Tarumoto, H., Ind. Eng. Chem. Res., 28, 1449-1452 (1989).

Oku, A. and Kimura, K., Chemistry Express, 5, 181-184 (1990).

Weiss, A. H. and Valinski, S., J. Catalysis, 74, 136 (1982). 

What is claimed is:
 1. A process for complete hydrodehalogenation of an aliphatic or alicyclic halogenated hydrocarbon to form a nonhalogenated hydrocarbon product, comprising contracting said aliphatic or alicyclic halogenated hydrocarbon in the gaseous phase with an elemental nickel-containing zeolite catalyst in the presence of a hydrogen donor at a temperature of about 300° C. to about 500° C.
 2. The process of claim 1 wherein the aliphatic halogenated hydrocarbon comprises a brominated, fluorinated, or chlorinated compound.
 3. The process of claim 1 wherein the hydrogen donor comprises hydrogen, water or methanol.
 4. The process of claim 1 wherein the hydrogen donor comprises water and hydrogen.
 5. The process of claim 1 wherein the hydrogen donor is hydrogen.
 6. The process of claim 1 wherein the catalyst is a nickel-containing ZSM-5 zeolite catalyst.
 7. The process of claim 6 wherein the catalyst contains from about 1% to about 35% nickel metal.
 8. The process of claim 6 wherein the catalyst contains from about 10% to about 20% nickel metal.
 9. The process of claim 1 wherein the hydrodehalogenation is initiated at a temperature between about 350° and 400° C.
 10. The process of claim 9 further comprising lowering the reaction temperature to about 325° C. after initiating the hydrodehalogenation.
 11. The process of claim 1 wherein the aliphatic halogenated hydrocarbon comprises at least 2 chlorine atoms.
 12. The process of claim 1 wherein the halogenated hydrocarbon comprises trichloroethane, trichloroethylene, dichloroethane, dichloroethylene, dichloromethane, trichloromethane, tetrachloromethane, tetrachloroethylene or dibromoethane.
 13. The process of claim 1 wherein the aliphatic halogenated hydrocarbon is a perhalogenated hydrocarbon.
 14. The process of claim 13 wherein the perhalogenated hydrocarbon comprises a fluorinated hydrocarbon.
 15. The process of claim 14 wherein the fluorinated hydrocarbon is trichlorotrifluoroethane.
 16. The process of claim 14 wherein the temperature is about 425° C. with a 10% Ni/ZSM-5/Al₂ O₃ catalyst at WHSV of about 0.99 hr⁻¹ and a hydrogen to catalyst ratio of about 30 to
 1. 17. The process of claim 13 wherein the aliphatic halogenated hydrocarbon is tetrachloroethylene. 